Device for dispensing at least one washing agent in a dishwashing machine

ABSTRACT

The dispensing device includes a support body adapted to be mounted on the side of that door of the machine which is facing the washing chamber, in a position such that in the operation this body is periodically flushed, at least in part, by a flow of washing liquid emitted by at least one spraying rotor. In the support body there is incorporated an electrically conducting member whose electric capacitance with respect to earth is variable by the effect of the flow of washing liquid which periodically impinges onto the body; a detection and processing device being connected to the conducting member and being predisposed for detecting the variations of the electric capacitance of said conducting member with respect to earth and for correlating in a predetermined manner said variations with the operation of the spraying rotor.

The present invention relates to a device for dispensing at least onewashing agent in a dishwashing machine having a washing chamber which isclosed by a door and in which there is mounted at least one sprayingrotor for spraying a washing liquid.

More specifically the invention relates to a dispensing devicecomprising a support body adapted to be mounted on that side of the doorwhich is towards the washing chamber, in a position such that in theoperation said body is periodically flushed, at least in part, by a flowof washing liquid emitted by said at least one rotor.

One object of the present invention is to provide a dispensing device ofthe type specified above, which by simple and inexpensive means allowsthe modalities of operation of the abovementioned at least one sprayingrotor to be detected.

This and other objects are achieved in accordance with the invention bymeans of a dispensing device of the type specified above, characterizedin that in the support body there is incorporated an electricallyconducting member whose electric capacitance with respect to earth isvariable by the effect of the flow of washing liquid which periodicallyimpinges onto said body; detection circuit means being connected to saidconducting member and being predisposed for detecting the variations ofthe electric capacitance of the conducting member with respect to earthand for correlating in a predetermined manner said variations with theoperation of said at least one spraying rotor.

In accordance with another feature, in the support body of thedispensing device there is defined at least one receptacle intended toreceive an amount of a washing agent, and to which there is attached afurther electrically conducting member which is likewise incorporated inthe support body and whose electrical capacitance with respect to earthis variable as a function of the quantity or level of the washing agentin said receptacle, and in which detection circuit means are coupled tosaid further conducting member and are predisposed to detect variationsof the electrical capacitance thereof with respect to earth.

Other features and advantages of the invention will become apparent inthe course of the following detailed description, which is given purelyby way of non-restrictive example, with reference to the appendeddrawings, in which:

FIG. 1 is a near-front perspective view of a dispensing device accordingto the present invention;

FIG. 2 is a diagrammatic side view of the dispensing device shown inFIG. 1; and

FIG. 3 is a block-type circuit diagram of an embodiment of theelectrical/electronic part of a dispensing device in accordance with thepresent invention.

In FIGS. 1 and 2 the number 1 is a general reference for a deviceaccording to the invention for dispensing a washing agent in adishwashing machine.

Referring particularly to FIG. 2, the dishwashing machine M comprises awashing chamber 2 which is closed on one side by a door 3. Mountedinside the washing chamber 2 is at least one spraying rotor of a typealso known per se. In the illustrative embodiment shown schematically inFIG. 2 there are three spraying rotors SP1, SP2 and SP3 which arerespectively the upper, intermediate and lower rotors.

B1, B2 and B3 are the respective jets of washing liquid emitted by theserotors.

The dispensing device or dispenser 1 is mounted on that side of the door3 which is towards the washing chamber 2, in a position such that, inthe operation said body is periodically flushed, at least in part, bythe flows of washing liquid B1, B2 and B3 emitted by said rotors.

Although the embodiment illustrated by way of example in FIG. 2 hasthree rotors, the invention is not in any way limited to this number,but is applicable also in particular to the case in which the washingchamber of the dishwashing machine has only one or two spraying rotors.

The dispensing device 1 comprises a supporting body 4 in the form of forexample a plastic moulding.

With reference to FIG. 1, the supporting body 4 contains two separatereceptacles 5 and 6 shown in long and short dashes.

The receptacle 5 is in the shape of a tub, for example, and is designedto hold an amount or dose of a washing agent such as a detergent, e.g.in liquid or powder form. This receptacle is normally closed by amovable lid 7 which can be made to open in a manner known per se bymeans of an associated electrically driven actuator controlled by acontrol unit which controls the operation of the dishwashing machine.

The receptacle 6 is designed to contain an amount of another washingagent, such as rinse aid. This amount is usually equal to a plurality ofdoses, deliverable in succession, in the course of successive washcycles.

Although the receptacles 5 and 6 in FIG. 1 are shown, for purelyillustrative reasons, as essentially parallelepiped-shaped, this shapeis in no way binding as these receptacles can be a great variety ofdifferent shapes.

Referring to FIGS. 1 and 2, the supporting body 4 of the dispensingdevice incorporates an electrically conducting member or electrode 10,e.g. in the form of an elongate metal strip, or possibly a conductingwire.

The electrical capacitance of the conducting member 10 with respect toearth is subject to variation during operation due to the flow ofwashing liquid periodically directed at the dispensing device 1 by theor each spraying rotor.

In the illustrated example of an embodiment, other conducting members 11and 12 are attached to the receptacles 5 and 6, respectively, for thewashing agents (see FIG. 1 in particular).

The electrical capacitances with respect to earth of these furtherconducting members 11 and 12 will vary in response to the amount orlevel of washing agents contained in the associated receptacles 5 and 6.

The conducting members 10, 11 and 12 may conveniently be incorporated inthe supporting body 4 of the dispensing device during its moulding.

These conducting members are connected to detection and processingcircuit devices which will be described later with reference to theconducting member 10, it being understood that the conducting members 11and 12 are connected to the same or similar detection and analysiscircuit devices.

With reference to FIG. 2, the dispensing device 1 comprises a detectionand processing circuit device denoted as a whole by the number 20,comprising for example a microprocessor 21. This detection andprocessing circuit device may conveniently be mounted directly on thebody of the dispensing device 1, and may be interfaced with the unit ECUwhich controls the operation of the dishwasher by means of a connection22. The latter may simply be a single-wire serial link.

The detection and processing circuit device 20 is connected to earth E,or to the neutral conductor of the AC power supply line, for example byconnecting it (directly or via unintended impedances) to the earthconductor or conductors of the dishwashing machine.

This device 20 is connected to the conducting members 10, 11 and 12 andis designed to detect variations in their respective electricalcapacitances with respect to earth E.

The detection and processing device 20 is designed in particular tocorrelate the variations of capacitance with respect to earth of theconducting member 10 with the operation of the spraying rotor or rotors.

On the other hand, the same device 20 is designed to detect variationsin the capacitance of the conducting members 11 and 12 with respect toearth E, and to correlate them in predetermined ways with the quantitiesor levels of washing agents contained in the associated receptacles 5and 6.

With reference to the block diagram, FIG. 3, in the embodiment whichthis illustrates schematically and by way of example, the detection andprocessing device 20 comprises an excitation stage 30 suitable forapplying high-frequency electrical excitation signals A, B and C to theconducting members or electrodes 10, 11 and 12, respectively, and anacquisition stage 31 for acquiring, for each of said conducting membersor electrodes, corresponding respective low-frequency response signalsa, b, c, which are influenced by the respective electrical capacitanceswith respect to earth of said conducting members or electrodes.

The response signals acquired by the stage 31 are passed to a filter FIR32, whose output is connected to the input of an up-down counter 33.

The output of the counter 33 is connected to a unit 34 which runs ananalytical algorithm. This receives a feedback signal from theacquisition stage 31 via a feedback unit 35. The unit 34 also receives,from a unit 36, the predefined parameter values which definecharacteristics of the spraying rotor or rotors of the dishwashingmachine, and characteristics of the receptacles containing theaforementioned washing agents.

Lastly, the unit 34 is connected to an output unit 37 which producessignals indicating the modes of operation of the spraying rotor orrotors, and signals indicating the amounts or levels of washing agentsin the respective receptacles. These signals are sent via the link 22 tothe control unit ECU of the dishwashing machine.

Analysis of the response signals obtained from the conducting member orelectrode 10 allows the device to discriminate between the followingconditions: correct rotation of the spraying rotor or rotors, slowrotation (not correct) of one or more rotors, and one or more rotors notworking.

The response signals obtained by the conducting members or electrodes 11and 12 allow continuous monitoring of the amount or level of washingagents in the associated receptacles.

Clearly, without departing from the principle of the invention, theembodiments and details of construction may vary considerably from thosedescribed and illustrated purely by way of non-restrictive example,without thereby departing from the scope of the invention as defined inthe following claims.

1. A device for dispensing at least one washing agent in a dishwashingmachine having a washing chamber which is closed by a door and in whichthere is mounted at least one spraying rotor for spraying a washingliquid; the dispensing device comprising a support body adapted to bemounted on the side of the door facing the washing chamber, in aposition such that in the operation said body is periodically flushed,at least in part, by a flow of washing liquid emitted by said sprayingrotor; wherein in said support body there is incorporated anelectrically conducting member whose electric capacitance with respectto earth is variable by the effect of the flow of washing liquid whichperiodically impinges onto said body; detection and processing circuitmeans, coupled to earth, being connected to said conducting member andbeing predisposed for detecting the variations of the electriccapacitance of said conducting member with respect to earth and forcorrelating in a predetermined manner said variations with the operationof said spraying rotor.
 2. A dispensing device according to claim 1,wherein in said support body there is defined at least one receptacleintended to receive an amount of a washing agent, and to which there isattached a further electrically conducting member which is likewiseincorporated in the support body and whose electrical capacitance withrespect to earth is variable as a function of the quantity or level ofthe washing agent in said receptacle, and in which detection andprocessing circuit means are coupled to said further conducting memberand are predisposed to detect variations of the electrical capacitancethereof with respect to earth.
 3. A dispensing device according to claim1, wherein the detection circuit means are predisposed to apply to theor each conducting member a respective high-frequency electricexcitation signal and to acquire from the or each conducting member acorresponding low-frequency electrical response signal influenced by therespective electrical capacitance with respect to earth, and to analysein predetermined ways said or each response signal.
 4. A dispensingdevice according to claim 1, wherein said at least one spraying rotor isrotatable about an essentially vertical axis, and said conducting memberhas an elongate shape and extends in such a way that in the operation itis at least approximately horizontal.
 5. A dispensing device accordingto claim 2, wherein said at least one further conducting member has anelongate shape, and extends in such a way that in the operation it is atleast approximately vertical.